A massive new study sheds light on how cannabis affects the brain, particularly during cognitive tasks.
Researchers analyzed over 1,000 young adults and found that both heavy lifetime use and recent cannabis consumption significantly reduced brain activity during working memory tasks. This impairment was linked to worse performance on tasks requiring focus, problem-solving, and instruction-following. Brain imaging revealed that key regions responsible for decision-making and attention were affected.
Cannabis Use and Brain Function: A Groundbreaking Study
A new study published in JAMA Network Open examines how both recent and long-term cannabis use affects brain function during cognitive tasks.
As the largest study of its kind, researchers analyzed over 1,000 young adults aged 22 to 36 using brain imaging technology. They found that 63% of heavy lifetime cannabis users showed reduced brain activity during a working memory task, with a similar impact seen in 68% of recent users.
Reduced Brain Activity and Working Memory Impairment
This decrease in brain activity was linked to poorer performance on working memory — a crucial function that helps people retain and use information for tasks. For instance, working memory enables someone to follow instructions, mentally visualize concepts, or solve problems like math equations.
“As cannabis use continues to grow globally, studying its effects on human health has become increasingly important. By doing so, we can provide a well-rounded understanding of both the benefits and risks of cannabis use, empowering people to make informed decisions and fully comprehend the potential consequences,” said the study’s first author Joshua Gowin, PhD, assistant professor of radiology at the University of Colorado School of Medicine on the University of Colorado Anschutz Medical Campus.
In the study, heavy users are considered young adults who’ve used cannabis more than 1000 times over their lifetime. Whereas, using 10 to 999 times was considered a moderate user, and less than 10 times was considered a nonuser.
MRI Scans Reveal Cannabis’ Impact on Brain Function
The researchers studied the neural response of participants during a magnetic resonance imaging (MRI) session and gave them seven cognitive tasks to complete. The tasks tested working memory, reward, emotion, language, motor skills – such as tapping a finger to map brain control, relational assessment and theory of mind.
The researchers found that cannabis had a statistically significant effect on brain function during working memory tasks, meaning the observed impact is very unlikely to be due to random chance. This effect was seen in both recent and lifetime cannabis users. The impact was less significant for the other tasks.
“We applied the highest standards to our research, setting rigorous thresholds for statistical significance across all seven cognitive function tests. To minimize the risk of false positives, we employed false discovery rate (FDR) correction. While some of the other tasks indicated potential cognitive impairment, only the working memory task showed a statistically significant impact,” adds Gowin.
Key Brain Regions Affected by Heavy Cannabis Use
During working memory tasks, the researchers found heavy cannabis use appeared to reduce brain activity in certain areas of the brain (dorsolateral prefrontal cortex, dorsomedial prefrontal cortex, and anterior insula). These regions of the brain are involved in important cognitive functions such as decision-making, memory, attention, and emotional processing.
However, Gowin mentions their research also suggests that abstaining from using cannabis before doing a cognitive task could help to improve performance. “People need to be aware of their relationship with cannabis since abstaining cold turkey could disrupt their cognition as well. For example, heavy users may need to be more cautious,” Gowin says.
Unanswered Questions: The Future of Cannabis Research
He adds, “There are a lot of questions we still need answers to regarding how cannabis impacts the brain. Large, long-term studies are needed next to understand whether cannabis use directly changes brain function, how long these effects last, and the impact on different age groups.”
Reference: “Brain Function Outcomes of Recent and Lifetime Cannabis Use” by Joshua L. Gowin, Jarrod M. Ellingson, Hollis C. Karoly, Peter Manza, J. Megan Ross, Matthew E. Sloan, Jody L. Tanabe and Nora D. Volkow, 28 January 2025, JAMA Network Open.
DOI: 10.1001/jamanetworkopen.2024.57069
News
New MRI Study Reveals How Cannabis Alters Brain Activity and Weakens Memory
A massive new study sheds light on how cannabis affects the brain, particularly during cognitive tasks. Researchers analyzed over 1,000 young adults and found that both heavy lifetime use and recent cannabis consumption significantly reduced brain [...]
How to Assess Nanotoxicity: Key Methods and Protocols
With their high surface area and enhanced physicochemical properties, nanomaterials play a critical role in drug delivery, consumer products, and environmental technologies. However, their nanoscale dimensions enable interactions with cellular components in complex and [...]
Nanotech drug delivery shows lasting benefits, reducing need for repeat surgeries
A nanotechnology-based drug delivery system developed at UVA Health to save patients from repeated surgeries has proved to have unexpectedly long-lasting benefits in lab tests – a promising sign for its potential to help human patients. [...]
Scientists Just Found DNA’s Building Blocks in Asteroid Bennu – Could This Explain Life’s Origins?
Japanese scientists detected all five nucleobases — building blocks of DNA and RNA — in samples returned from asteroid Bennu by NASA’s OSIRIS-REx mission. NASA’s OSIRIS-REx mission brought back 121.6 grams of asteroid Bennu, unveiling nitrogen-rich organic matter, including DNA’s essential [...]
AI-Designed Proteins – Unlike Any Found in Nature – Revolutionize Snakebite Treatment
Scientists have pioneered a groundbreaking method to combat snake venom using newly designed proteins, offering hope for more effective, accessible, and affordable antivenom solutions. By utilizing advanced computational techniques and deep learning, this innovative [...]
New nanosystem offers hope for improved diagnosis and treatment of tongue cancer
A pioneering study has unveiled the Au-HN-1 nanosystem, a cutting-edge approach that promises to transform the diagnosis and treatment of tongue squamous cell carcinoma (TSCC). By harnessing gold nanoparticles coupled with the HN-1 peptide, [...]
Global Trust in Science Is Stronger Than Expected – What’s Next?
A landmark global survey conducted across 68 countries has found that public trust in scientists remains robust, with significant support for their active involvement in societal and political matters. The study highlights the public’s [...]
Microplastics in the bloodstream may pose hidden risks to brain health
In a recent study published in the journal Science Advances, researchers investigated the impact of microplastics on blood flow and neurobehavioral functions in mice. Using advanced imaging techniques, they observed that microplastics obstruct cerebral blood [...]
AI Surveillance: New Study Exposes Hidden Risks to Your Privacy
A new mathematical model enhances the evaluation of AI identification risks, offering a scalable solution to balance technological benefits with privacy protection. AI tools are increasingly used to track and monitor people both online [...]
Permafrost Thaw: Unleashing Ancient Pathogens and Greenhouse Gases
Permafrost is a fascinating yet alarming natural phenomenon. It refers to ground that remains frozen for at least two consecutive years. Mostly found in polar regions like Siberia, Alaska, and Canada, permafrost plays a [...]
Frequent social media use tied to higher levels of irritability
A survey led by researchers from the Center for Quantitative Health at Massachusetts General Hospital and Harvard Medical School has analyzed the association between self-reported social media use and irritability among US adults. Frequent [...]
Australian oysters’ blood could hold key to fighting drug-resistant superbugs
Protein found in Sydney rock oysters’ haemolymph can kill bacteria and boost some antibiotics’ effectiveness, scientists discover An antimicrobial protein found in the blood of an Australian oyster could help in the fight against [...]
First U.S. H5N1 Death Sparks Urgency: Scientists Warn Bird Flu Is Mutating Faster Than Expected
A human strain of H5N1 bird flu isolated in Texas shows mutations enabling better replication in human cells and causing more severe disease in mice compared to a bovine strain. While the virus isn’t [...]
AI Breakthrough in Nanotechnology Shatters Limits of Precision
At TU Graz, a pioneering research group is leveraging artificial intelligence to drastically enhance the way nanostructures are constructed. They aim to develop a self-learning AI system that can autonomously position molecules with unprecedented precision, potentially [...]
How Missing Sleep Lets Bad Memories Haunt Your Mind
Research reveals that a lack of sleep can hinder the brain’s ability to suppress unwanted memories and intrusive thoughts, emphasizing the importance of restful sleep for mental health. Sleep deprivation has been found to [...]
WHO issues new warning over ‘mystery virus’ and calls for return of COVID restrictions
The World Health Organization (WHO) has called for the reinstatement of restrictions implemented during the COVID-19 pandemic as cases of human metapneumovirus (HMPV) continue to surge. While hospitals in China are overwhelmed with positive [...]
